Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description adds substantial extra context: auth required, no inputs, secret and headers are redacted, previous_secret_active is true only for 24h post-rotation, previous secret is never returned, and specific failure codes (401/403).

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the usage condition, then the return shape, then edge-case semantics and error codes. Sentences are dense but each earns its place. The inline return object is long, though justifiable given there is no output schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema and no input params, the description fully compensates by documenting the returned object fields, redaction behavior, rotation semantics, scoping behavior, and failure modes. Nothing an agent needs to invoke or interpret the result is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Zero parameters, so the schema carries nothing to clarify and the baseline is 4. The description correctly notes 'No inputs,' which is all that can be said here.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('list the webhooks on this account') plus the scope (account-level, inbox-scoped keys behave differently). It is clearly distinguishable from siblings like register_webhook, update_webhook, delete_webhook, and rotate_webhook_secret.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Use this when you need the webhooks on this account' gives clear context, and the inbox-scoped-key note tells the agent when results differ. However, it names no alternative or exclusion (e.g., point to register/update/rotate for mutations), so it stops short of the 5-level explicit routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.